INVESTIGATIONS OF AG(100)-IN AND AG(111)-IN INTERFACES WITH LOCAL PROBES

The structure of Ag(100)In and Ag(111)In interfaces and the formation of AgIn2 were studied with the perturbed γ-γ angular correlation method using radioactive 111In probe atoms. At the Ag(111)In interface the probe atoms experience a strong electric field gradient with the z principal axis perpendicular to the interface, which reflects an ordered interface structure. This can be explained by epitaxial growth of the very thin indium film on the Ag(111) substrate. In both systems, interdiffusion starts at around 240 K and leads to the formation of the interfacial alloy AgIn2. Since the same behaviour has been observed for polycrystalline AgIn thin film couples, this result rules out grain-boundary-assisted diffusion of indium in silver as the mechanism for AgIn2 compound formation. Further experiments indicate that the AgIn2Ag interface profile is rather uneven. This result may be explained by grain-boundary-assisted diffusion of silver in indium at the onset of AgIn2 compound formation. © 1990.